Jenna Dewan and Steve Kazee Welcome Son Callum Michael Rebel: 'Our Hearts Exploded'

Everly is a big sister!

The 6½-year-old’s mom Jenna Dewan gave birth to her second child (and first with fiancé Steve Kazee) on Friday, March 6, both parents shared on Instagram Tuesday.

Alongside a black-and-white snapshot of herself holding her newborn baby boy for the first time, Dewan wrote, “And just like that, our hearts exploded into all of eternity and beyond ❤️🌈❤️ Welcome to the world you little angel! ❤️,” before sharing her son’s birth date and full name: Callum Michael Rebel Kazee.

“In an instant our universe burst wide open and nothing would ever be the same. Welcome to earth star child,” Kazee captioned a shot of Callum’s tiny hand.

The new baby is the first child for Tony winner Kazee, 44, while actress and dancer Dewan, 39, shares daughter Everly with ex-husband Channing Tatum.

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A source confirmed to PEOPLE in October 2018 that Dewan and Kazee, who won the Tony Award for his performance in the Broadway production Once, had been “dating for a couple [of] months” and that the Flirty Dancing host was “very happy” in her new relationship.

Then, PEOPLE confirmed Dewan’s pregnancy this past September, with the couple telling PEOPLE exclusively, “We are beyond overjoyed and couldn’t be happier to be expanding our family!”

In October 2019, the then-parents-to-be posed for a photo spread with PEOPLE, when Dewan shared that there “was excitement all around” upon learning of her pregnancy — especially for Everly!

“She is going around lifting up my shirt to literally anyone, and goes, ‘I’m going to be a big sister! Did you know there’s a baby in my mommy’s belly? Do you want to touch it?’ ” the Gracefully You author said with a laugh. “She will just lift up my shirt. She kisses [my belly].”

Dewan shared her daughter’s enthusiasm about the baby — save for the talking-to-strangers/lifting-up-her-shirt part of the equation.

“I always said that I would love to expand my family. I was so excited by the option to do that and excited by that. And so the second I knew, I was thrilled with it,” she told PEOPLE.

Naturally, part of her happiness over her bundle of joy was due to her growing relationship with Kazee, whom Dewan praised as having been a “divine gift” in her life.

“It’s this electric connection that just works. It’s been one of the biggest blessings in my life that I never saw coming,” the World of Dance star said. “The timing felt right. Expanding our family was something that was important to both of us and it just flowed.”

RELATED VIDEO: Jenna Dewan Is Pregnant! Actress Expecting First Child with Boyfriend Steve Kazee

The couple was seen moving into a new home together on the actress’s 39th birthday in December. Kazee confirmed the news the same day in his sweet birthday post for Dewan.

In the photos, Kazee (who regularly raves about his fiancée on social media) and a very pregnant Dewan stood outside their new home, surrounded by boxes as people helped move their things inside.

“The day of her birth has been a full one for us so far … dropping off the kiddo at school, baby doc appointment, nursery planning, moving into our new home, picking the kiddo up from school and so many other little life moments,” the Shameless actor wrote in his birthday tribute to Dewan.

“Through it all I love catching eyes with her and knowing that she is the person I will be spending the rest of my life with,” Kazee added.

RELATED GALLERY: From Partners to Parents: A Timeline of Jenna Dewan and Steve Kazee’s Relationship

Dewan and Kazee announced their engagement last month, sharing the happy news on Instagram alongside a photo of the couple sharing a kiss.

“A lifetime to love and grow with you…you have my heart ❤️,” the Step Up actress captioned her post.

In his own post’s caption, Kazee quoted the song “Let It Breathe” by Water Liars: “When you wake in the morning I will kiss your face with a smile no one has ever seen / When you wake in the morning I will kiss your eyes and say it’s you I have loved all these years.”

In the photo, Dewan also gave fans a look at her impressive and unusual engagement ring. The star said “yes” to a gold-banded ring that actress and Bayou with Love founder Nikki Reed helped Kazee create.